This invention relates to a vacuum switching tube with a ring to generate an axial magnetic field.
The innovation addresses a vacuum switching tube with two switching devices of basically cylinder-disk shaped design. The switching devices can be moved in relation to one another and are attached to a bearing post. In order to generate an axially directed magnetic field, a galvanic open ring is attached to the back of the switching devices. The galvanic open ring is in contact with the bearing post via a radially arranged conductor device.
A vacuum switching tube of this type has been described in the publication 80 SM 700-F IEEE PAS during the summer meeting of 1980. In this case, the ring has approximately the same outer diameter as the actual switching device and is subdivided into quadrants in the direction of its circumference. Each of these quadrants is connected to the respective conductor device extending from the center. Over this connection the current flows from the bearing post to the quadrant. To provide current flow to the switching device the free ends of the quadrants of the ring are provided with elevations. Furthermore, the switching device has several radial slots to suppress the eddy current during zero current crossing. However, these slots limit the switching capacity of the vacuum switching tube, because the light arcs have the tendency to settle at the edges where they cause increased burn-up with corresponding metallic vapor formation. It is also known, that an axial magnetic field can be generated by a field coil attached to the outside of the vacuum sealed housing (DE-A29 11 706). Although this configuration does not limit the design of the switching device, the field coil requires considerable conductor material and space.